EXHAUST GAS RECIRCULATION APPARATUS FOR INTERNAL COMBUSTION ENGINE AND METHOD OF CONTROLLING EXHAUST GAS RECIRCULATION APPARATUS

• US 20090038308A1
• Filed: 04/20/2007
• Published: 02/12/2009
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Nagae, Masahiro
• Granted Patent: US 8,006,494 B2
• Time in Patent Office: Days
• US Class Current: 60/602
• CPC Class Codes: F01N 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F02B 37/24 by using pumps or turbines with adjustable guide vanes
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/0055 Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/12 for deceleration F02D41/0005, F02D41/107 take precedence
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/126 transitional corrections at the end of the cut-off period
• CPC Class Codes: F02D 9/04 concerning exhaust conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/06 Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
• CPC Class Codes: F02M 26/10 having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/24 with two or more coolers
• CPC Class Codes: F02M 26/37 with temporary storage of recirculated exhaust gas internal exhaust gas recirculation F02M26/01
• CPC Class Codes: F02M 26/60 in response to air intake pressure
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A variable-geometry turbocharger and a low-pressure EGR passage are provided. The variable-geometry turbocharger includes a turbine provided in an exhaust passage, and a compressor provided in an intake passage. In the variable-geometry turbocharger, the cross sectional area of a path through which exhaust gas passes is adjusted by adjusting the opening degree of a nozzle vane. The low-pressure EGR passage connects the area of the exhaust passage downstream of the turbine to the area of the intake passage upstream of the compressor. The EGR gas is recirculated to the intake passage through the low-pressure EGR passage. The EGR gas is directed to flow through the low-pressure EGR passage when a vehicle is decelerating or when fuel supply to the internal combustion engine is cut off. The pressure in the intake passage is adjusted toward a target pressure by adjusting the opening degree of the nozzle vane when the EGR gas flows through the low-pressure EGR passage.

Claims

1-20. -20. (canceled)

21. An exhaust gas recirculation apparatus for an internal combustion, comprising:

a variable-geometry turbocharger that includes a turbine provided in an exhaust passage, and a compressor provided in an intake passage, wherein a cross sectional area of a path through which exhaust gas passes is adjusted by adjusting an opening degree of a nozzle vane;

a low-pressure EGR passage that connects an area of the exhaust passage downstream of the turbine to an area of the intake passage upstream of the compressor, and through which EGR gas, which is part of exhaust gas discharged from an internal combustion engine, is recirculated to the intake passage;

a deceleration-EGR portion that directs the EGR gas to flow through the low-pressure EGR passage when the vehicle is decelerating or when fuel supply to the internal combustion engine is cut off; and

a deceleration-supercharging portion that adjusts a pressure in the intake passage toward a target pressure by adjusting the opening degree of the nozzle vane when the deceleration-EGR portion directs the EGR gas to flow through the low-pressure EGR passage.

22. The exhaust gas recirculation apparatus according to claim 21, wherein when the deceleration-EGR portion directs the EGR gas to flow through the low-pressure EGR passage, the deceleration-supercharging portion decreases the opening degree of the nozzle vane.

23. The exhaust gas recirculation apparatus according to claim 21, further comprising:

a low-pressure EGR valve that adjusts an amount of EGR gas that flows through the low-pressure EGR passage; and

an exhaust throttle valve that adjusts an amount of exhaust gas that flows through an area of the exhaust passage downstream of where the low-pressure EGR passage is connected to the exhaust passage, wherein the deceleration-EGR portion directs the EGR gas to flow through the low-pressure EGR passage by making an opening degree of the low-pressure EGR valve greater than that when the low-pressure EGR valve is fully closed, and making an opening degree of the exhaust throttle valve smaller than that when the exhaust throttle valve is fully open.

24. The exhaust gas recirculation apparatus according to claim 23, wherein the deceleration-EGR portion fully opens the low-pressure EGR valve and fully closes the exhaust throttle valve when the vehicle is decelerating or when the fuel supply to the internal combustion engine is cut off.

25. The exhaust gas recirculation apparatus according to claim 21, further comprising:

a low-pressure EGR valve that adjusts an amount of EGR gas that flows through the low-pressure EGR passage; and

a first intake throttle valve that adjusts an amount of intake air that flows through an area of the intake passage upstream of where the low-pressure EGR passage is connected to the intake passage, wherein the deceleration-EGR portion directs the EGR gas to flow through the low-pressure EGR passage by making an opening degree of the low-pressure EGR valve greater than that when the low-pressure EGR valve is fully closed, and making an opening degree of the first intake throttle valve smaller than that when the first intake throttle valve is fully open.

26. The exhaust gas recirculation apparatus according to claim 25, wherein the deceleration-EGR portion fully opens the low-pressure EGR valve and fully closes the first intake throttle valve when the vehicle is decelerating or when the fuel supply to the internal combustion engine is cut off.

27. The exhaust gas recirculation apparatus according to claim 21, further comprising:

a low-pressure EGR valve that adjusts an amount of EGR gas that flows through the low-pressure EGR passage;

an exhaust throttle valve that adjusts an amount of exhaust gas that flows through an area of the exhaust passage downstream of where the low-pressure EGR passage is connected to the exhaust passage; and

a first intake throttle valve that adjusts an amount of intake air that flows through an area of the intake passage upstream of where the low-pressure EGR passage is connected to the intake passage, wherein the deceleration-EGR portion directs the EGR gas to flow through the low-pressure EGR passage by making an opening degree of the low-pressure EGR valve greater than that when the low-pressure EGR valve is fully closed, and making an opening degree of the exhaust throttle valve smaller than that when the exhaust throttle valve is fully open, and making an opening degree of the first intake throttle valve smaller than that when the first intake throttle valve is fully open.

28. The exhaust gas recirculation apparatus according to claim 27, wherein the deceleration-EGR portion fully opens the low-pressure EGR valve, and fully closes the exhaust throttle valve and the first intake throttle valve when the vehicle is decelerating or when the fuel supply to the internal combustion engine is cut off.

29. The exhaust gas recirculation apparatus according to claim 21, further comprising:

a high-pressure EGR passage that connects an area of the exhaust passage upstream of the turbine to an area of the intake passage downstream of the compressor, and through which the EGR gas is recirculated to the intake passage; and

a high-pressure EGR valve that adjusts an amount of EGR gas that flows through the high-pressure EGR passage, wherein the deceleration-EGR portion makes an opening degree of the high-pressure EGR valve smaller than that when the high-pressure EGR valve is fully open.

30. The exhaust gas recirculation apparatus according to claim 29, wherein the deceleration-EGR portion fully closes the high-pressure EGR valve when the vehicle is decelerating or when the fuel supply to the internal combustion engine is cut off.

31. The exhaust gas recirculation apparatus according to claim 29, further comprising:

an air-fuel ratio storage portion that stores an air-fuel ratio immediately before the vehicle starts decelerating or immediately before the fuel supply to the internal combustion engine is cut off, and

an air-fuel ratio adjusting portion that adjusts an actual air-fuel ratio toward a target air-fuel ratio by adjusting the opening degree of the high-pressure EGR valve based on the air-fuel ratio stored by the air-fuel ratio storage portion.

32. The exhaust gas recirculation apparatus according to claim 21, further comprising:

a high-pressure EGR passage that connects an area of the exhaust passage upstream of the turbine to an area of the intake passage downstream of the compressor, and through which the EGR gas is recirculated to the intake passage;

a high-pressure EGR valve that adjusts an amount of EGR gas that flows through the high-pressure EGR passage;

an air-fuel ratio storage portion that stores an air-fuel ratio immediately before the vehicle starts decelerating or immediately before the fuel supply to the internal combustion engine is cut off; and

an air-fuel ratio adjusting portion that adjusts an actual air-fuel ratio toward a target air-fuel ratio by adjusting an opening degree of the high-pressure EGR valve based on the air-fuel ratio stored by the air-fuel ratio storage portion.

33. The exhaust gas recirculation apparatus according to claim 31, wherein the air-fuel ratio adjusting portion causes burned gas to flow through the high-pressure EGR passage by adjusting the opening degree of the high-pressure EGR valve after fuel injection starts.

34. The exhaust gas recirculation apparatus according to claim 32, wherein the air-fuel ratio adjusting portion causes burned gas to flow through the high-pressure EGR passage by adjusting the opening degree of the high-pressure EGR valve after fuel injection starts.

35. The exhaust gas recirculation apparatus according to claim 31, further comprising:

a second intake throttle valve that adjusts an amount of intake air that flows through an area of the intake passage downstream of the compressor, wherein the air-fuel ratio adjusting portion controls an opening degree of the second intake throttle valve based on the stored air-fuel ratio.

36. The exhaust gas recirculation apparatus according to claim 32, further comprising:

a second intake throttle valve that adjusts an amount of intake air that flows through an area of the intake passage downstream of the compressor, wherein the air-fuel ratio adjusting portion controls an opening degree of the second intake throttle valve based on the stored air-fuel ratio.

37. The exhaust gas recirculation apparatus according to claim 35, wherein the air-fuel ratio adjusting portion decreases the opening degree of the second intake throttle valve after fuel injection starts.

38. The exhaust gas recirculation apparatus according to claim 36, wherein the air-fuel ratio adjusting portion decreases the opening degree of the second intake throttle valve after fuel injection starts.

39. A method of controlling an exhaust gas recirculation apparatus for an internal combustion engine, which includes a variable-geometry turbocharger that includes a turbine provided in an exhaust passage, and a compressor provided in an intake passage, wherein a cross sectional area of a path through which exhaust gas passes is adjusted by adjusting an opening degree of a nozzle vane;

and a low-pressure EGR passage that connects an area of the exhaust passage downstream of the turbine to an area of the intake passage upstream of the compressor, and through which EGR gas, which is part of exhaust gas discharged from an internal combustion engine, is recirculated to the intake passage, the method comprising;

directing the EGR gas to flow through the low-pressure EGR passage when a vehicle is decelerating or when fuel supply to the internal combustion engine is cut off; and

adjusting a pressure in the intake passage toward a target pressure by adjusting the opening degree of the nozzle vane when the EGR gas is directed to flow through the low-pressure EGR passage.

40. The method of controlling the exhaust gas recirculation apparatus according to claim 39, further comprising:

directing the EGR gas to flow through the low-pressure EGR passage by making an opening degree of a low-pressure EGR valve greater than that when the low-pressure EGR valve is fully closed, and making an opening degree of an exhaust throttle valve smaller than that when the exhaust throttle valve is fully open, wherein the low-pressure EGR valve adjusts an amount of EGR gas that flows through the low-pressure EGR passage, and the exhaust throttle valve adjusts an amount of exhaust gas that flows through an area of the exhaust passage downstream of where the low-pressure EGR passage is connected to the exhaust passage.

41. The method of controlling the exhaust gas recirculation apparatus according to claim 39, further comprising:

directing the EGR gas to flow through the low-pressure EGR passage by making an opening degree of a low-pressure EGR valve greater than that when the low-pressure EGR valve is fully closed, and making an opening degree of a first intake throttle valve smaller than that when the first intake throttle valve is fully open, wherein the low-pressure EGR valve adjusts an amount of EGR gas that flows through the low-pressure EGR passage; and

the first intake throttle valve adjusts an amount of intake air that flows through an area of the intake passage upstream of where the low-pressure EGR passage is connected to the intake passage.

42. The method of controlling the exhaust gas recirculation apparatus according to claim 39, further comprising:

making an opening degree of a high-pressure EGR valve smaller than that when the high-pressure EGR valve is fully open, when the vehicle is decelerating or when the fuel supply to the internal combustion engine is cut off, wherein the high-pressure EGR valve adjusts an amount of EGR gas that flows through a high-pressure EGR passage; and

the high-pressure EGR passage connects an area of the exhaust passage upstream of the turbine to an area of the intake passage downstream of the compressor, and the EGR gas is recirculated to the intake passage through the high-pressure EGR passage.

43. The method of controlling the exhaust gas recirculation apparatus according to claim 42, further comprising:

storing an air-fuel ratio immediately before the vehicle starts decelerating or immediately before the fuel supply to the internal combustion engine is cut off; and

adjusting an actual air-fuel ratio toward a target air-fuel ratio by adjusting the opening degree of the high-pressure EGR valve based on the stored air-fuel.